With A-level and GCSE exams drawing to a close today, several schools said that students faced timetable clashes. There was near consensus that the number of exams needed to be reduced.
Glenda Coles, an exams officer at 2,128-pupil Whitchurch high school in Cardiff, which handles up to 50 exam sittings in one day, said: "We gain more expertise every year, but the system does not get any easier."
Bonnie Ellis, exams officer at Colchester sixth-form college, which had 2,000 students sitting papers, said: "We are struggling with the number of exams - it gets very complicated. Unit exams for subjects like business studies and classic civilisation may require three one-hour sessions which run back to back. It is a long time for the students to concentrate."
There were also concerns that last year's A-level regrading fiasco may have affected students' confidence.
Malcolm Noble, head of Bexleyheath school in south London, said: "Their anxiety is palpable - you can feel it."
However, David Adelman, principal of Godalming college, Surrey, said: "The Government has done a reasonable job restoring confidence in the system.
Last year's problems are water under the bridge."
But he said students were being needlessly pressurised by the number of exams and that teaching was distorted, with "spoon feeding" exam preparation taking up too much time.
* Meanwhile, this could be the last year that private school league tables are published in August.
The Headmasters' and Headmistresses' Conference is to discuss abolishing the collective publication of results after two-thirds of its 649 members voted against the system last year.
For 11 years, members have volunteered exam results in August, but many favour individual publications on school websites. Abandoning this approach would make it difficult for newspapers to include fee-paying schools in league tables before the start of term. Statistics would not be available until November.